This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to Patent Application Serial No. MI 2000 A 002760 filed in Italy on Dec. 20, 2000. The entire content of which is hereby incorporated by reference.
This invention relates to methods and apparatus for activating and controlling sorting units in a sorting machine in which items are loaded onto, and unloaded from, movable sorting units in a direction transversely of a direction of travel of the units. Preferably the sorting units are of the xe2x80x9cCross Beltxe2x80x9d type, wherein the sorting units consist of conveying belts mounted on supports moving along a fixed path and capable of being activated to receive and unload the carried objects in a direction perpendicular to the direction of motion of the sorting machine.
Each trolley is provided with an on-board electronic unit, capable of controlling the electric motor activating the trolley""s conveying belt.
According to the invention, this electronic unit consists of a printed circuit comprising a few loops of a length nearly matching the pitch of the trolley, which generate a control signal to activate the unloading motor, whenever a ground-level induction set opposite each outlet is energized.
The branch dealing with sorting machines has in recent years witnessed a considerable diffusion of sorting machines known as a xe2x80x9cCross Beltxe2x80x9d type.
These are installations in which a series of trolleys moves along a fixed linear path, a circle etc., while receiving the objects to be sorted whenever it passes some loading stations, so as to unload them in the planned collecting stations.
The trolley is usually equipped with a conveying belt capable of rotating independently in the two directions orthogonal to the direction of motion of the sorting machine.
The electric motors actuating the belts are activated during the loading phase of the objects, to ensure their precise positioning both at the moment of their unloading as well as for the precise routing of the objects to their appropriate destination, and the controlling of these sorting units is entrusted to a programmable controller (OLC, PC etc.), based on known technologies.
The purpose of this invention is to provide a simple and economical solution capable of using a sorting machine for orthogonal belts, with the resulting advantages, even in plants with a long path and a low number of outlets.
For these applications, the technologies already available for controlling the orthogonal sorting machines are not economically justified, as they involve complications without a commensurate value.
This invention refers to an equipment and a method capable of receiving the signals from said controlling devices, and of consequently activating the sorting unit needed for unloading the objects.
Various systems for controlling unloading belts are known at the present state of the art.
British Patent 2,218,957, for example, describes a sorting machine in which each trolley is equipped with a motor actuator, as well with gliding contacts which collect the activating controls originating from the control system from appropriately selected busways set opposite every sorting machine area where an activation is expected, for instance next to the collecting devices.
When the sorting unit passes the area in which it must be activated, the control system sends a signal to the actuating unit, which transfers the motor""s power to the unit, so as to start the rotation of the small belt and unload the transported object.
The electrical power is brought on-board the trolley by a system of busways running along the sorting path together with the busway sections.
This type of activating mode is valid but demands a high number of sectioned busways, gliding contacts and their relative wirings, in order to enable the control system to send out its signals to each trolley.
If one considers that a sorting system generally comprises hundreds of separate collecting devices which involve the need for as many sections and wirings, and that the trolleys in such systems often also run into the hundreds, it can easily be grasped that a control system as described above can be complex and costly.
European Patents No. 0 556 866 and No. 0 481 341 describe a sorting system where the trolleys are equipped with on-board intelligent units which allow them to eliminate the sectioned busways along with their relative sliding contacts and electrical wirings.
This system provides for sending out some control signals through the continuous busways, which are decoded and interpreted by the processing units on-board the trolleys and forwarded to the motor activating units. The entire train of trolleys is normally subdivided in groups, each comprising only a few trolleys, where only one xe2x80x9cmasterxe2x80x9d trolley is equipped with sliding contacts, thus greatly reducing the overall number of contacts installed. The electrical power is on the contrary picked up from continuous busways running along the path.
This system is particularly effective in applications requiring a very high number of destinations, but is less so, for solely cost-related reasons, in applications with a limited number of destinations.
In applications involving sorting machines of great length or having a low number of outlets along their path, the great sophistication of having on-board controls is in fact not economically justified.
A further system for simplifying these installations provides for generating the electrical power for the belt activating motor by using batteries installed on-board and kept charged by alternators, which mechanically derive their motion from the very motion of the sorting machine.
The activation is controlled by infrared ray signals, generated by an emitter set opposite each collecting device.
On-board the trolley, a receiver decodes and interprets the infrared signal and actuates the belt through an activating unit.
However, even this system exhibits a number of problems, because it is sensitive to external influences such as intense and direct light, dirt or the like, moreover, every trolley or at any rate a considerable number of trolleys must be equipped with various expensive equipment items such as batteries, alternators and the like.
This also means a high complexity of the controlling system on-board.
At the state of the art, there are finally some sorting machines of the xe2x80x9cCross Beltxe2x80x9d type, which provide for certain ground-level mechanical devices engaging with other devices on the trolleys, designed to rotate the belt.
This latter system is rather cumbersome, considerably expensive, noisy and troublesome, especially from the mechanical maintenance viewpoint.
This invention intends eliminating the mentioned drawbacks in the applications having a low number of outlets, with a minimum number of on-board controls which must in any event allow operating at the values actually perceived in these applications.
Reliability: the trolley motor must be controlled by an on-board actuating system capable of ensuring its use within its operating limits.
Accuracy: the conveying belt must be activated at a controlled accelerating and speeding rate, so that the speed profile during the sorting process can be repetitive and largely independent of the weight of the sorted object.
Flexibility: the activating point pertaining to each outlet must be variable, based on an sw-signal, to allow a number of trajectories for the sorting of objects. The various trajectories are chosen based on the characteristics of the objects, the speed of the sorting machine, or the best distribution of the objects sorted inside the outlet. The duration of activating the belt must be variable in order to allow for correcting the position of the transported object.
In order to satisfy the mentioned requirements, while using the simplifications made possible by the type of dedicated applications (low number of outlets, possibility for a single type of speed ramp (accelerating the final speed, thanks to larger outlets), a solution was developed which envisions a simple actuating system, associated with the motor whose only control parameters (actuating point, activating direction, etc.) are easily controlled from the ground, while exploiting the laws of electromagnetic induction in a simple manner. A magnetic induction field is generated at a station and transmitted to an electronic unit on the trolley, which activates a device for unloading items in response to detecting the induction field.